"""
   ┌─┐       ┌─┐ + +
┌──┘ ┴───────┘ ┴──┐++
│                 │
│       ───       │++ + + +
███████───███████ │+
│                 │+
│       ─┴─       │
│                 │
└───┐         ┌───┘
    │         │
    │         │   + +
    │         │
    │         └──────────────┐
    │                        │
    │                        ├─┐
    │                        ┌─┘
    │                        │
    └─┐  ┐  ┌───────┬──┐  ┌──┘  + + + +
      │ ─┤ ─┤       │ ─┤ ─┤
      └──┴──┘       └──┴──┘  + + + +
             神兽保佑
            代码无BUG!
"""
import sys
from PyQt5.QtWidgets import QWidget, QPushButton, QApplication, QMessageBox
from PyQt5.QtCore import QCoreApplication


class Example(QWidget):

    def __init__(self):
        super().__init__()

        self.initUI()

    def initUI(self):
        self.setGeometry(300, 300, 250, 150)
        self.setWindowTitle('Message box')
        self.show()

    def closeEvent(self, event):

        reply = QMessageBox.question(self, 'Message',
                                     "Are you sure to quit?", QMessageBox.Yes |
                                     QMessageBox.No, QMessageBox.NO)

        if reply == QMessageBox.Yes:
            event.accept()
        else:
            event.ignore()


if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())


